Today, mobile operators are using Wi-Fi to offload traffic from the mobile networks. However, the opportunity to improve end user experience regarding performance is also becoming more important. The current Wi-Fi deployments are completely separate from mobile networks, and are to be seen as non-integrated. The usage of Wi-Fi is driven due to the free and wide unlicensed spectrum, and the increased availability of Wi-Fi in mobile terminals like smartphones and tablets. The end users are also becoming more and more at ease with using Wi-Fi for example at offices and homes.
The different business segments for Wi-Fi regarding integration possibilities can be divided into mobile operator hosted/controlled vs. 3rd party hosted/controlled Wi-Fi Aps. As an example, a 3rd party is seen as any other entity other than mobile operator and that the 3rd party is not totally “trusted” by the mobile operator. The 3rd party could be for example a Wi-Fi operator or an end-user him/herself. In both segments, there exist public/hotspot, enterprise and residential deployments.
Wi-Fi integration towards the mobile core network is emerging as a good way to improve the end user experience further. These solutions consist mainly of the components: common authentication between 3GPP and Wi-Fi, and integration of Wi-Fi user plane traffic to the mobile core network. The common authentication is based on automatic SIM-based authentication in both access types. The Wi-Fi user plane integration provides the mobile operator the opportunity to provide the same services such as parental control and subscription based payment methods for the end users when connected both via 3GPP and via Wi-Fi. Different solutions are standardized in 3GPP: Overlay solutions (S2b, S2c) and integration solutions (S2a) are specified in 3GPP (S2a, S2b, S2c indicating the 3GPP interface/reference point name towards the PDN-GW). These solutions are specified in 3GPP TS 23.402.
FIG. 1 shows the network architecture for E-UTRAN and EPC and how the eNodeB is connected via the S1-interfaces, S1-MME and S1-U to the MME and Serving GW respectively. It also shows how the Wi-Fi access network is connected to the PDN-GW via the S2a interface (that is trusted Wi-Fi access) and to the 3GPP AAA Server via the STa interface. FIG. 2 illustrates a conventional deployment for untrusted Wi-Fi access.
One problem with the conventional deployment of Wi-Fi access is extensive signaling in handover scenarios. In this regard, when UE handover occurs between LTE and Wi-Fi, the session on the other side is always taken down. For example, if the UE handovers a PDN connection from the LTE to WLAN using S2a/S2b to PGW, the LTE session in MME, SGW and PGW is removed and a new session for WLAN is created. If dedicated bearers are used on LTE, the PGW has to re-create them on WLAN access network. If the UE handovers to LTE, the WLAN session in the PGW is removed and a new LTE session is created in the MME, SGW and PGW. If dedicated bearers are used on the WLAN, the PGW have to re-create them on LTE. FIG. 17 illustrates an example of the creation of bearers on the LTE side. The re-creation of bearers results in inefficient signaling. Additionally, the latency of the handover can be extensive. Furthermore, the PGW must use the S6b/Diameter interface when UE attach to WLAN to set the PGW id in HSS if handover is to be supported. Additionally, the S6b procedure towards HSS will also increase the HSS load. The S6b procedure also increases the AAA load.
Another problem with the conventional deployment of Wi-Fi access is that no location information for untrusted access is available. In this regard, when untrusted WLAN is used, no location information is received on the S2b interface, which results in the PGW being unable report any valuable location information to the PCRF.
Another problem with conventional deployment of Wi-Fi access is that the UE is in control of access selection. In this regard, it is very hard for the PGW to perform access steering when S2a/S2b is used toward the PGW. For instance, if UE is connected to LTE and initiate a handover to WLAN. Then, theoretically the PGW can deny the attempt if UE have very good connectivity/user experience on LTE but the PGW do not have such information regarding the network condition on the LTE side. This is mainly due to that PGW is a gateway node serving many accesses and logically it shouldn't need information about the access network.